Film-feeding mechanism



Sept 12 195 Q. WETTEL ETAL,

FILM-FEEDING MECHANISM Filed April 1, 1949 FIG.5.

. OTTO WITTEL Z7 Z8 3] VERNON H. JUNGJOHANN INVENTORS ATTORNEYS Patented Sept. 12, 1950 Otto Wittel and Vernon H. Jungjohann, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application April 1, 1949, Serial No. 85,006

The present invention relates to intermittent film-feeding devices, such as used on motioarr-pio-v ture apparatus, although not limited to this use alone.

It is well known in the art to provide intermittent film-feeding mechanisms of the type in which the claw arm extends laterally of the film to be fed and must be pivoted fiatwise to permit the claw to move into and out of engagement withthe film. perforations, and must also be pivoted. edgewise to feed the film'a step at a time. Examples of. such intermittent film-feeding mechanisms are those shown in the following patents: S. 2,168,771, issued August 8, 1939; U. S. 2,214,186, issued September 10, 1940; U. S. 2,335,435, issued November 30, 19l3.

One problem confronting the designers of such intermittent feeding mechanisms is to provide a simple, rugged, and efficient pivot assembly for the claw arm which will permit both an edgewise and fiatwise pivotal movement thereof. As evidenced by the noted prior art, different approaches to the solution of this problem have involved the use of a complicated and relatively delicate universal type joint for the pivoted end of the claw, or making the claw rigid as respect to edgewise pressure but including a portion which is resilient in a fiatwise direction to permit the desired in-and-out movement of the claw. Since these mechanisms run at fairly high speed, and are ofttimes abused by the operators, pivot assemblies which are subject to wear, fatigue, and, require careful handling, are not considered satisfaotory.

One object of the present invention is to provide an intermittent film-feeding mechanism of the type including a claw arm which extends laterally of the film to be fed, and must move edgewise as well as fiatwise in feeding the film and having a new and novel pivot assembly which permits this double pivotal movement of the arm.

Another object of the present invention is to provide an intermittent film-feeding mechanism of the type set forth having a pivot assembly for the claw arm which is simple, rugged, efilcient, practically frictionless, permits the use of a claw arm, rigid in both planes, automatically compensates for Wear, and is easy to assemble.

Another object is to provide a pivot assembly for an intermittent film pull-down of the type set forth which, though so constructed that the parts are resiliently held in place, is provided with a safety mechanism to prevent the assembly from being. accidentally disconnected due to heavy or otherwise abnormal loads being applied thereto.

15 Claims. ('01. 88..1-8.4)

'A further object is to provide a pivot. assembly for tin-intermittent film pull-down of the type set forth which permits the mechanism to be readily adjusted for framing and/or altering the length 'o-fthe pull-down stroke of the claw arm.

Another object is to provide a pivot assembly fora pull-down claw of the type set forth which consists essentially of one or more balls onwhich the claw arm is mounted to pivot in. at least two different directions.

And, still another object is to provide a pivot assembly of the type set forth wherein the claw arm is held in rolling contact with one or more balls by spring pressure, and so constructed that by changing the point of said spring pressure the claw arm may be biased about its pivot point in either direction fiatwise by a desired amount to supplement, or supplant, a spring and/or cam usually acting on the claw arm intermediate its ends for this purpose.

The novel features that we consider characteristicof our invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its methods of operation, together with additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawe ings, in which:

Fig. 1 is a partial elevational view of a motionpicture projector incorporating a film pull-down mechanism constructed in accordance with a preferred embodiment of the present invention;

Fig. 2 is a horizontal sectional view taken substantially on line 2--2 of Fig. 1; l

Fig. 3 is an enlarged vertical sectional view taken substantially on line 33 of Fig. 1;

Fig. .4 is an enlarged vertical sectional view taken substantially on line 4-4 of Fig. 1;

Fig.v 5 is an enlarged horizontal sectional View taken substantially on line 5-5 of Fig. 1; and

; Fig; Bis an'enlarged elevational detail showing a modification in the position of the pressure point ofthe pivot assembly which provides a bias for the claw arm in one direction fiatwise.

Like reierence characters refer to corresponding parts throughout the drawings.

Essentially, the present invention comprises a rigid claw. arm adapted to extend laterally of the film to be fed and provided with a ball-joint pivot assembly at the end opposite that carrying the film claw which permits the claw arm to pivot edge-wise, as well as fiatwise, as required in advancingthe film step-by-step. The parts constitutingthe pivot assembly are held in assembled relation by a spring and, by rearranging the point at which this spring pressure is applied relative to the pivot point of the arm, the claw arm can be biased in either direction fiatwise, or can be left unbiased in this respect. Means are provided for positively limiting the amount of lateral movement which the pivoted end of the claw arm is capable of, so that the pivot assembly will not become accidentally disconnected should an excessive or abnormal load be applied thereto for any reason. i

While, for purposes of disclosure, we have shown our improved film-feeding mechanismincorporated in a motion-picture projector, "this claw mechanism can also be used on a motionpicture camera having a ratchet-type pull-down mechanism, as will be fully described hereinafter.

Referring now to the drawings, we have shown.

a motion-picture projector comprising a easing l0 including a transverse wall provided with an opening 12 past which a film F is adapted to be moved by the intermittent feed mechanism to be described. The film F is moved stepwise past aprojection aperture l3 in a suitable gate memberl4, and which aperture is illuminated by any suitable illuminating system of which" we have shown only the condenser lens assembly IS. The projector will also include an objective, not shown, for'projecting the image of the frame of film in the aperture l3 onto a suitable screen, as is well known.

The light beam is repeatedly cut off from the projection'aperture I3 by a rotating sectorshutter l6 which is fixed to a rotatable shaft 11 extending substantially parallel to the optical axis 6f the projector and supported in a boss I8 in the Wall by bearing means including ballbearing l9" held in place in the boss by a plurality of bolt a'nd'w'asher combinations 2t. The's'hutter i6 is provided with a depressed flange l6 which is eng'a'ge'd by a driving'belt B connected in turn to a pulley'on the motor shaft, not shown. Accordingly, the shutter acts as a large pulley for driving the shaft I! to which the other feeding mechanism of the projector may be operatively conn'ectd in any suitable manner "Coming now to the intermittent film-feeding mechanism, this includes a rigid'clawarm 2| extending laterally of the film to be fed and pivoted at its left-hand end, looking at Figs. 1 and 2, by a novel pivot assembly in accordance with the present invention, and to be fully described hereinafter. The right-hand end of the claw arm is provided with one or more claws, or teeth 22, turned at right angles to the body of the claw arm, and which are adapted to engage the perforations 23 in thefilm strip F to feed the same. In the arrangement shown, the up-and-down reciprocal movement of the claw arm' edgewise for feeding the film strip F isunder the control of a peripheral cam 24 fixed to the shutter shaft H; the claw arm 2| being provided intermediate its ends with a follower 25 for engaging this cam. The claw arm 2| is normally moved upwardly by the arm'26 ofa double-ended spring 21 located on alug 28 on the wall II and having its other end, or arm, 21 anchored against a boss 29 extending from the side wall 30 of the casing, see Figs. 1, 2, 4-an'd 5. As most clearly shown in Figs. 4 and 5, the spring 21 is held on the lug 28 by a capping plate 3|, and the arm 25 thereof engages, and is confined by, a flanged collar 32 rotatably mount ed-onthe-stud 33-which fixes the cam follower 25 to the claw arm. Accordingly, the arm26 of the spring '21 provides the forceto pivot the clawup- 4 wardly or to a raised position, while peripheral cam 24 only controls the extent of this upward movement but moves the claw arm downward edgewise for its film-feeding stroke.

In the arrangement disclosed, the claw is adapted to be completely retracted from the film path for movement to its raised position and to again be moved into engagement with a successive film perforation prior to the subsequent feeding stroke of the claw. To this end, the arm 26 of the-spring 21 is bent laterally, as shown at 34 in Fig. 2, to normally exert a pressure against the inside .face of the claw arm to pivot it in a flatwise direction away from the film. The movement of the claws on the claw arm into engagement with the film is effected by a face cam 35 onto the shutter shaft H, and engaged by the front vertical face of the follower 25. The peripheral cam 24, the face cam 35, and the shutter [6 must be oriented relative to one another on the shutter shaft in such a way that the shutter willcut off the projection beam only during the time-the claw is moving downwardly to ad Vance the film, and the claws will be engaged with the film 'for the pull-down stroke and disengaged for the return stroke. To insure and maintain this proper orientation, we provide the shutter with a turned-up ear 36 adapted to engagean opening in each of the peripheral cam and'face cam. This car may also serve to connect these cams to the shutter to rotate therewith, rather than keying'them separately to the shutter shaft.

We are aware that film-advancing mechanisms, having a claw arm movement substantially the same as that set forth, are well known in the art, and the present invention is not found in the mechanism described up to this point per se. The present invention is concerned primarilywith a new and novel pivot assembly (now to be described) for the left-hand end of the claw arm which will permit the arm to pivot in both an edgewise direction for feeding the film and a fiatwise direction to permit retraction and insertion of the claw from and into the film perforations and still allow the use of a claw arm which is rigid in all planes.

Coming'now to the pivot assembly we have devised for the claw arm, it comprises a stationary plate 49 fixed tothe boss 29 and a companion boss 29' on the side wall 36 of the casing it to lie in a plane substantially parallel to the film path at the gate and the claw arm 2|. The face of this plate 40 adjacent the claw arm is provided with a ball seat or socket ll in which a pivot ball 22; is seated in rotating contact therewith. The'faoeof the'left-hand end of the claw arm adjacent the plate 46 is also provided with a seat or socket 43 which is adapted to be held in contact with pivot 42'. This ball accordingly constitutes the pivot point for the claw arm and is of such'a diameter as to space the claw arm a sufficient distance from the plate to allow a pivoted movement of the arm in a fiatwise direction as required to move the claw 22 into and out of the film path, aswell as to "allow the desired reciprocal movement of the claw arm in an edgewise direction necessary to the feeding movement of the claw.

To hold the claw arm 2| in assembled relation on the pivot ball 62, we provide a rather strong leaf spring is fixed adjacent one end to the stationary plate by a bolt 45, and having its free end 46 pressing against a ball 41 rotatably mounted ina seat 48 in the opposite face of the claw arm. The fixed end of this spring is slottedat' lilil to engage a stud Ill! extending from the plate 49 to prevent the spring from turning in its own plane. To maintain the left-hand end of the claw arm in substantially parallel relation with the plate 40, and to prevent the spring 44 from tripping the arm about the pivot ball 52, we locate a third ball 49 between the claw arm and the plate. To hold this ball in place, the inside face of the claw arm is provided with a seat 59 in which the ball rolls. The ball 48 is located so that a line connecting its center with that of the pivot ball, 42 lies substantially at right angles to the longitudinal axis of the claw arm, or parallel to the film path at the gate. Accordingly, the two balls 42am 39, in combination, act as a hinge for the claw arm, permitting it to pivot fiatwise as necessary. In

the arrangement disclosed, the pressure ball 41' is located on the line joining the centers of the other two balls so as to combine therewith to provide an unbiased hinge for the'claw arm. The ball seats 48 and 5B for the balls M and 49, respectively, may be slightly elongated, as shown in Fig. l, to allow these balls to roll slightly as the claw arm pivots edgewise about the pivot ball 42. Even though these balls are allowed to roll slightly along the claw arm as the latter reciprocates edgewise about pivot ball 42, they will automatically center themselves and maintain the relative disposition above set forth therefor.

In order to prevent the pivot assembly from being pulled apart under an abnormal claw load, the left or pivoted end of the claw arm is provided with a turned-down ear 5i which extends into a'slot 52 in the stationary plate All. This slot and ear are each proportioned so as to allow the claw arm to move freely over a given range, but positively prevent the pivoted end of the claw to move in an abnormal manner which would act to pull the pivot assembly apart. An example of an abnormal movement of the claw arm, which this safety arrangement is to provide for, is the case where the film might, for some reason, be held against movement at the timethe claw tries to advance it. As the result of such a condition, the pull-down cam 25 would attempt to move the claw arm downwardly, and, if the claw end thereof were unable to move, an abnormal load would be applied to the pivoted end of the claw arm in a downward direction, and which might pull the pivot assembly apart because of its spring mounting. The described safety mechanism consisting of the ear and slot would positively prevent this abnormal movement, or pressure, from disconnecting the pivot assembly.

This pivot assembly is readily adjusted to vary the length of stroke of the claw and/or to provide a framing adjustment. For instance, to accomplish a framing adjustment, the pivot point of the claw arm must be moved up and down, or in the direction of film movement. This is done with the present pivot assembly by providing the stationary plate M with elongated slots 55 engaging the shank of the flanged bushings 55, which, in combination with bolts Bl, hold the plate on the bosses 29. For adjusting the plate up and down by virtue of these elongated slots, a lever 58 extending at right angles to the plate and pivoted intermediate its ends at til has a slotted end to engaging a stud 6 l on the lower end of the plate. By pivoting the lever 58 in the direction indicated by the double arrow and by any suitable adjusting means, not shown, the pivot assembly may be shifted up and down for framing purposes.

To adjust thelength of stroke of the claw, it is necessary to move the pivot point of the claw laterally or the film path and the peripheral cam 24, and thereby vary the lever ratio of the cam. This is readily accomplished by making the shank of-the lower bushin 'tfi, on which the slots in the plate 40 b'ear,'in -the form of an eccentric, as clearly shown in Fig. 3. By turning the bushing 56, the'plat'e t0, and the pivot assembly, can be moved sideways. Thefiange of the bushing may be made in the form of a hexagon, as shown, to facilitate adjustment of the bushing by a wrench. A spring washer 63 is located between the flange of the'bushing 5t and the plate dB to provide friction for holding the plate in any one of its positions of adjustment, sidewise or lengthwise. Ordinarily, sumcient sidewise adjustment of plate it! to vary the length of the claw stroke can be accomplished from one end of the plate, but

should more adjustment be needed, or in fact twice as much, the upper end of the plate may be mounted on an adjustable eccentric bushing like in the art, that the present invention is readily adapted and desirable for other embodiments of pull-down mechanisms. For example, this pulldown mechanism, as disclosed, could be used on a motion-picture camera, as well as a projector. It could also be used on pull-down mechanism of the ratchet type, which type of mechanism is generally limitedto use on cameras because of the fact that the claw is dragged along the edge of the film during the upstroke. As is well known in the art, in the ratchet type of pull-down mechanism, the claw is normally biased in the direction of the film and drops into the film perforation at'the top of the return stroke of the claw by virtue of this bias. The upper edge of the claw is inclined relative to the film path so that, as the claw starts its upstroke, the engagement between theinclined top of the claw and the upper edge of the engaged perforation earns the cla-W'out of the perforation and rides along the face of the film'during the entire return stroke of the claw.

The present pull-down mechanism could be readily converted'to one of the ratchet type by properly shaping the tops of the claws to give the desired camming action, by rearranging the arm 2t of spring 2'! to act in the other direction, and on the other side of the claw arm 2| to force it toward the film, and disposing of the in -and-out face cam 35. The present pivot assembly is particularly adapted to such a modification in the pull-down mechanism, since it can do away with the need for the arm 26 of spring 2'! for forcing the claw arm toward the film. For instance, if this pivot assembly were to be used in this pull-down modified to be one of the ratchet type, the location of pressure'ball ll could be modified as shown in Fig. 6. As shown, the ball il is oifset to the right from the line joining the centers of the'balls 42 and 49 so that'the spring 44, in addition to. holding the pivot assembly together, serves to bias the claw arm fiatwise toward'the film; The amount of bias on the claw arm can be regulated by varying the amount by which the ball '41 is offset from the line of centers of the balls 42 and 49, about which the arm pivots, and we have found that a very smooth and eflective ratchet type pull-down of the ratchet type can be obtained by such a modification of the pivot assembly and without requiring any other biasing spring on the claw arm acting in this direction.

It will be understood that by shifting the ball t? to the left of the center line connecting the balls 42 and 49, a biasing action on claw arm 2| could be obtained to supplement, or even sup plant, that afforded by arm 26 of spring 21 due to its transverse bend 34. So long as this spring 21 is required to move the claw arm in an upward direction, when using a peripheral feeding cam as shown, there is no particular advantage in using the offset feature of ball 41 to obtain this desired bias. If, however, both the up-anddown stroke of the claw 2| were positively effected by a cam, i. e., if the claw arm included a box-type follower encasing a pull-down cam, and there was no need for th spring 21, then the offset feature of ball 41 could be advantageously used to obtain the desired bias on the claw arm and in a desired direction facewise about the pivot balls 42 and 49.

- From the above description it will be readily understood that we have devised a pivot assembly for film-feeding mechanisms of the type described which is relatively simple in construction, extremely rugged and eilicient in operation, and substantially frictionless. Because of the particular ball and spring mounting described, any wear which might be encountered between the balls and their seats, or sockets, will be automatically taken up by the spring 44 which serves to hold the parts in assembled relation. Furthermore, this particular pivot assembly is quite versatile in its applications to different types of pull-down mechanisms as evidenced by the two disclosed embodiments; namely a pull-down mechanism in which the claw is completely retracted from engagement with the film during the return stroke thereof, and a claw mechanism of the ratchet type in which the claw is biased in the direction of the film and is cammed out of the film perforation and rides along the film surface during the return stroke of the claw. This pivot assembly is also adapted for use in film-feeding mechanisms where the claw is positively driven in both the up-and-down stroke by a suitable cam and cam follower arrangement working in both directions, as well as in the modifications specifically disclosed where the claw is biased in one or two of its directions and cam-driven in the other two directions.

Although we have shown and described certain specific embodiments of our invention, we are fully aware that many modifications thereof are possible, and our invention, therefore, is not to be restricted to the precise details of construction shown and described, but is intended to cover all modifications coming within the scope of the appended claims.

: Having thus described our invention, what we claim is new and desire to secure by Letters Patent of the United States is:

1. In an intermittent film-feeding mechanism the combination of a rigid elongated claw arm extending laterally of the film to be fed, a claw on one end of said arm and extending substantiallyat right angles thereto, cam means engaging said claw arm -intermediate its ends and adapted to control movement of the claw arm flatwise to and from the film and edgewise in proper timed relationpto advance the film one frame at a time, and means for pivoting the other end of said claw arm to allow both the de-. sired fiatwise and edgewise movement thereof, said last mentioned means comprising a stationary member, and a ball-joint between the end of said claw arm and said stationary member permitting said claw arm to pivot in all directions relative to said stationary member, and including a ball disposed between said stationary member and the end of said claw arm which spaces said arm from said member and permits it to pivot thereon in all directions.

2. An intermittent film-feeding mechanism according to claim 1, characterized by a pin and slot connection between the pivoted end of said claw arm and said stationary member positively restricting the amount of movement the pivoted end of said claw is capable of relative to said stationary member to prevent accidental disconnection of said ball joint due to excess loads on said pivot assembly.

3. In an intermittent film-feeding mechanism the combination of a rigid elongated claw arm extending laterally of the film to be fed, a claw on one end of said arm and extending substantially at right angles thereto, cam means engaging said claw arm intermediate its ends and adapted to control movement of the claw arm fiatwise to and from the film and edgewise in proper timed relation to advance the film one frame at a time, and a pivot assembly for the other end of said claw arm to allow both the desired fiatwise and edgewise movement thereof and comprising a first ball seat formed in one face of the end of the claw arm, a stationary plate having a face parallel to the claw arm and provided with a ball seat complementary to that in the claw arm, a ball located in each of said seats and holding said claw arm and stationary plate in spaced relation suflicient to permit the desired fiatwise pivotal movement of the arm, and means including a spring for pressing the end of said arm toward said plate to hold the arm and ball in assembled relation on said plate.

4. In an intermittent film-feeding mechanism the combination of a rigid elongated claw arm extending laterally of the film to be fed, a claw on one end of said arm and extending substantially at right angles thereto, cam means engaging said claw arm intermediate its ends and adapted to control movement of the claw arm fiatwise to and from the film and edgewise in proper timed relation to advance the film one frame at a time and a pivot assembly for the other end of said claw arm to allow both the desired fiatwise and edgewise movement thereof and comprising a first ball seat formed in one face of the end of the claw arm, a stationary plate having a face parallel to the claw arm and provided with a ball seat complementary to that in the claw arm, a ball located in each of said seats and holding said claw arm and stationary plate in spaced relation suificient to permit the desired flatwise pivotal movement of the arm, a second ball located between the stationary plate and the adjacent face of said claw arm at a point spaced from said first ball in a direction substantially normal to-the longitudinal axis of said arm and means for applying spring pressure to the other face of said claw arm at a point disposed between said two mentioned balls for holding the balls and claw arm in assembled relation and permitting the desired pivotal motion of the arm.

i intermittent film-feeding mechanism according to claim 4 in which the means for applying spring pressure to the other face of the claw arm is disposed to act at a point inr'a line joining said .two mentioned balls, whereby the two balls and the point at which pressure is applied'by' said spring: pressing means actas a hinge permitting a fiatwise pivotal movement of the arm without bias in either direction.

6. An intermittent film-feeding mechanism according to claim 4 in which the means for applying spring pressure to the other face of the claw arm is disposed to' act at a point to one side of a line joining said two mentioned balls whereby the claw end of' the arm is biased in a; fiatwise direction toward or from the film depending upon which side of the line joining said balls said spring pressure is applied.

'7. In an intermittent film-feeding mechanism the combination of a rigid-elongated claw arm extending laterally of the film to be fed, a claw on one end of said arm and extending substanthe other end of said claw arm and provided with a ball seat, a ball rotatably disposed in said seat, the face of said claw arm adjacent said plate provided with a ball seat complementary to the seat in said plate and adapted to engage said ball and be held in spaced relation from said plate thereby so as to be free to pivot thereon in both a fiatwise and edgewise direction, a second ball rotatably positioned between the adjacent faces of said plate and claw arm at a point remote from said first ball and in a direction substantially normal to the longitudinal axis of said claw arm, and a third ball intermediate said other two and engaging the opposite face of the claw arm, and a spring member for applying pressure to said third ball to force the claw arm toward said stationary plate and hold the parts of the pivot assembly in operative relation.

8. An intermittent film-feeding mechanism according to claim 4 and including a pin and slot connection between said pivoted end of said claw arm and said stationary plate for positively limiting the amount of lateral movement the pivoted end of said claw arm is capable of in a direction counter to its normal film-feeding movement and thereby prevent the pivot assembly from being pulled apart by an abnormal load due to abnormal functioning of the feeding mechanism.

9. An intermittent film-feeding mechanism according to claim 4 and including said stationary plate provided with a slot, an ear turned down from said pivoted end of the claw arm and extending into said slot, said ear and slot disposed and proportioned to allow a normal pivoting action of said claw arm but adapted to prevent the pivotal movement of the arm in an abnormal manner, and thereby eliminate the possibility of said pivot assembly from being disconnected by an abnormal movement of the claw arm.

10. In an intermittent film-feeding mechanism the combination of a rigid elongated claw arm extending laterally of the film to be fed, a claw on'one end of said arm and extending substantially at right angles thereto, cam means enga ing said claw-arm intermediate its ends" and adapted tocont'rol'movement of the claw arm fiatwiseto and from the film and edgewise in propertimed relation to advance the film a step at'a time, and including an in-and-out face cam f-orcontrolling the movement of the claw arm fiatwise, a spring. normally urging said claw arm into-contact with said in-and-out cam, and a pivot assembly for the other end of said claw-arm to-allow both the desired fiatwise and edgewise movement thereof and comprising a stationary f plate parallel to the other end of said claw arm and; provided with a ball seat, a first ball seat formed in the face of said claw member adjacent said r'ilata-a ball engaging each of said seats and holding said arm and plate in a spaced relation sufficient to permit the desired fiatwise pivgo otal movement of the claw arm as wellas the desired edgewise movement, a second ball disposed in rolling contact between the adjacent faces of said arm and plate and located in spaced relation to said first ball in a line substantially normal to the longitudinal axis of said claw arm, a third ball engaging the other face of said arm at a point between and on a line joining said first two balls, and a spring member for applying pressure through said third ball to said claw arm to force it toward said plate to hold said parts in assembled relation while permitting the desired pivotal movement of the arm in all directions.

11. An intermittent film feeding mechanism according to claim 10 in which said canimeans also includes an up-and-olown peripheral cam for controlling the edgewise movement of the claw, said spring normally urging said clavv arm into contact with said in-and-out face cam also serving to urge the claw arm into contact with said up-and-down peripheral cam.

12. An intermittent film-feeding mechanism according to claim 10 in which said third ball is offset from the line joining said first two-mentioned balls in a direction such that the spring member acting on said third ball biases said claw arm in a direction about its pivot to supplement or supplant the spring normally urging said claw arm into contact with said in-and-out face cam.

13. In an intermittent perforated film-feeding mechanism the combination of a rigid elongated claw member extendin laterally of the film to be fed, a claw on one end of said arm and extending substantially at right angles thereto for engaging the film perforations, means for reciprocating said claw arm edgewise to feed the film a step at a time, and a pivot assembly for the other end of said claw arm allowing a pivotal movement of the claw arm fiatwise as well as edgewise to permit the claw to be moved into and. retracted from the film perforations in proper timed relation with the reciprocating action of the claw arm, and comprising a stationary plate parallel to the other end of said arm, a ball rotatably disposed in the surface of said plate so that its periphery extends beyond the plane thereof, a ball seat formed in the face of said arm adjacent said plate, means for holding said claw arm with its ball seat engaging said ball and said adjacent face normally parallel to said stationary plate while allowing rlatwise, as well as edgewise, pivotal movement of the claw arm on the surface of said ball, and spring means for I! normally biasing said claw arm in one direction fiatwise relative to the film path.

14. An intermittent film-feeding mechanism according to claim 13 in which said last-mentioned spring means comprises a spring acting on the claw arm at a point intermediate its ends.

15. An intermittent film-feeding mechanism according to claim 13 in which said means for holding said claw arm in engagement with said ball comprises an anti-friction spacer member between said stationary plate and the adjacent face of said claw arm to hold said claw arm substantially parallel with said plate, said spacer member spaced from said ball and so disposed relative thereto to allow said claw arm to pivot flatwise, an anti-friction member engaging the face of the claw arm opposite that adjacent the stationary plate and disposed between said ball .and said spacer member, a spring member acting on said anti-friction member in a, direction 30 to press said claw arm toward said plate and hold REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,168,771 HowelI Aug. 8, 1939 2.449-693 Fairbanks Sent. 21. 1948 

